How to Make Compost

How to Make Compost

It’s Not Rocket Science

With compost being so well-known as the key input to a thriving garden, I often wonder why more people don’t compost at home. Even a small backyard pile will go a long way.

I believe a big reason is that would-be composters don’t know where to start or become quickly overwhelmed. And that’s a shame, because it simply doesn’t have to be that way.

In nature, compost happens without any help from us. It’s simply the natural decomposition of organic matter over time by billions of microorganisms (bacteria and fungi mostly). To be sure, converting organic matter from its initial form to finished compost can be a very slow process. But we gardeners are generally a very impatient bunch. We want compost yesterday, not tomorrow! Fortunately, there are a few simple things we can do to speed up the process.

While the science behind composting can get quite impressive, home composters just don’t need to get bogged down in such details. Information abounds about the optimal carbon-to-nitrogen ratio (a.k.a., the brown-to-green ratio) to accelerate the composting process, for example. And that stops many would be composters dead in their tracks. I believe it’s one of the biggest impediments to getting started with home composting.

That said, having a good balance of browns to greens is indeed important for producing good compost quicker. Think of it like us having a balanced diet of nutrients in our body. Too much of one type, while not enough of the other, can have an impact on how our bodies function and how healthy we are.

The same is true during the composting process. The stars of the show in making compost are the billions of microorganisms breaking down all the raw inputs that consist of carbon and nitrogen. The microbes need some of both.

The closer you are to the proper ratio, combined with sufficient oxygen and moisture, and the billions of soil microbes will work fast and furious to break down the organic material as they consume the carbon and nitrogen. It’s this activity that generates the heat found in a compost heap during the composting process. The hotter the heap, the more in-balance your material is, and the faster it breaks down.

So what is the ideal carbon-to-nitrogen ratio? I will reluctantly tell you it’s about 25:1. But don’t glaze over here. While it does absolutely help in the speed of decomposition, your compost will eventually break down anyway.

If you’re curious about which ingredients are considered carbon-based vs. nitrogen-based, I have provided a list in a previous post of some of the most common ingredients you might add to a compost pile. Yet it still won’t tell the whole story. You can find it in an online search, but not here. It’s information overload and we’re breaking down the barriers to getting started, not putting them up.

MORE ON TEMPERATURE

So how hot is hot enough for compost to happen, even a little? While composting does take place down to as low as 50 F, you’ll be waiting a long time for the finished product The fastest composting takes place above 113 degrees F. In addition, higher sustained temperatures are necessary to destroy many unwanted elements in compost such as pathogens and weed seeds.

So here’s the good news: making compost is not rocket science. In fact making compost might be the easiest thing you do when it comes to gardening or growing. So don’t burden yourself with the science behind the details. In my years of making great compost, I’ve never worried about the ideal ratio. I make amazing, quick compost by just sticking to the basics and I’ll teach you how to do the same.

Allow me to walk you through the process and simplicity of making your own compost at home.

Just Four Ingredients

Imagine having a recipe that required only four ingredients to make the most awesome dish you’ve ever had. Even better, that recipe allowed for tons of substitutions. If you didn’t have one thing, you could substitute something else. And then, it didn’t require precise measurements, or even a certain temperature or cooking time.

Making compost is that simple—a four-ingredient recipe for the most awesome dish.

INGREDIENTS: Air, Water, Carbon (browns) and Nitrogen (greens)

TO PREPARE:

1. Combine generous portions of all ingredients and allow to cook outdoors for several months.

2. Continue to add ingredients until pile is approximate 4’ x 4’ x 4’.

3. Mix often (every week is good) and add water to moisten (about like a damp sponge).

Compost is ready to serve when the ingredients are unrecognizable, the internal temperature is ambient, and the contents smell rich and earthy. Add to existing garden soil at about 30% by volume and mix into the top four inches of any garden bed.

MORE ABOUT THE INGREDIENTS

When you understand that compost is made up of billions of beneficial microscopic living organisms, it’s easy to see why air and water would be key ingredients to sustaining life, even for the smallest forms of life.

Yet it’s this oxygen and moisture that allows them, and other organisms in the process, to utilize the other two ingredients -- carbon and nitrogen -- to biodegrade the raw material into finished compost.

AIR: Microorganisms can’t live without it. It’s that simple.

WATER: When it comes to remembering how wet your compost should be, think in terms of making and keeping it at the moisture level of a damp sponge. Now, if you want to know a little more, read on.

Greens and browns (reduced to small pieces), kept moist, and aerated by turning once a week or so goes a long way to making compost quickly.

Keeping your composting material consistently moist is a major factor in making compost faster.

THE RAW MATERIAL: Fortunately, you don’t have to know anything about science to figure out how to get a reasonable balance of the carbon (browns) and nitrogen (greens) into the mix. I think in terms of anything that came from the earth originally in some living plant form (no matter what it is today) is biodegradable and can be added into your composting system. And that’s pretty much my guide for considering what I put into my compost.

It also helps to know that all organic matter has varying amounts of both brown (carbon) and green (nitrogen) matter.

Common examples of brown waste ingredients include dried leaves, small twigs, yard debris, shredded paper and newspapers, paper towel rolls and brown paper bags.

Common examples of green waste include fresh grass clippings, plant trimmings and food scraps such as vegetables and salad greens… Oh, and coffee grounds.

Questionable Characters

A few common things you might be tempted to add to your compost should be avoided. (I should note some composters I know don’t subscribe to the following rules. But they are expert composters and consistently get their compost cooking hot enough to neutralize or eliminate the risks). If you want to play it safe, keep these out of your compost:

What Not to Add

FROM OUTSIDE

Weeds going to seed (you don’t want weed seeds surviving only to sprout in your garden compost next spring).

Diseased plants. While it’s possible the diseases won’t over-winter, the safe bet is to leave them out of your compost ingredients.

Animal waste (from carnivores).

Chemically-treated plants and grass. While most consumer lawn and garden chemicals break down rather quickly when exposed to the elements, some do not. In fact, they’re very persistent. If you want to avoid the risk of chemicals making it back into your garden, then simply keep them out of your compost pile to begin with.

WHAT NOT TO ADD FROM INSIDE

Animal products. This includes meat, bones, grease and dairy. Reasons to keep these away from your compost include the risk of potential disease pathogens, short term odor, and critter attractant. While all can be composted, that doesn’t mean you should. In home systems, lean toward the conservative side, especially when starting out.

Using Wood Ash in Compost

With the abundance of wood ash many of us deal with, especially in winter, this question always arises: can you put it in your compost pile?

The quick but qualified answer is yes, but only in moderation. While wood ash does have beneficial properties, it also can impact overall soil quality in an adverse way.

On the positive side, wood ash is high in potassium, phosphorus, calcium, boron, and other important nutrients plants need to grow. But it’s also free of nitrogen and very alkaline, which will raise the pH level in your compost or soil. Unless you have acidic soil to begin with, you don’t want to make alkaline soil even more so.

The pH of finished compost hovers around neutral (7.0). But adding an abundance of wood ash periodically throughout the composting cycle can raise the overall compost pH level into the alkaline range above what most plants need to thrive, even to a detrimental level. If you want to add some to your compost, do so, but only a small amount that you can mix in thoroughly to avoid high concentrations.

So if you can’t or shouldn’t add it to your compost, what can you do with it?

The easiest way to distribute a large amount of ashes all at once is to sprinkle them lightly and evenly over your lawn. Most lawns prefer a neutral pH. And many soils tend toward the acidic side. That’s why the recommendation for adding lime for lawn health is so common. It’s an easy way to raise the soil pH. And wood ash will do that also, but you’ll need about twice as much compared to lime.

Similarly, you can do the same thing around your trees, especially fruit trees, and particularly apples.

But don’t apply wood ash around acid-loving plants such as blueberries, rhododendrons, azaleas, camellias, and many native woodland plants.

Finally, before spreading ashes anywhere, get a soil test to know what your current soil pH is. The ash that you spread will raise the pH of the surrounding area. You may not need that. And don’t use ash from charcoal briquettes, or fake logs anywhere if you want to avoid the extra chemicals that these contain. At the very least, don’t add them to your compost.

Inoculants and Accelerators: Are They Worth it?

While Mother Nature and her workers do an amazing job of decomposing organic matter without our help, we’re an impatient bunch. In this day of nearly instant everything, we want our compost to be that, too. But the fact remains, composting is a process that can take a few to many months to finish in the home environment.

Even so, there are products marketed and sold that are said to speed up the process. Such additions are known as activators or accelerators. By definition, they are any substance that stimulates biological decomposition.

Inorganic, synthetic versions of activators are nitrogen-rich, chemicallyc synthesized compounds commonly found in fertilizers. These ingredients include ammonia, ammonium sulfate, urea and phosphate.

However, my opinion on synthetic activators is this: Why would you add these to your organic compost? It just goes against the spirit of building soil health, which comes from compost created the natural way.

Commonly-used natural activators are microorganism inoculants. When added to feedstock, they are believed to help break down organic matter faster. However, most studies have shown that adding these are unnecessary. The lack of microorganisms is rarely a problem as they are naturally present in abundance nearly all the time.

A second approach to making compost quicker is by providing extra food for the existing microbes in the form of nitrogen-rich material.

Some of the most common organic, nitrogen-rich food activators include manure, dried blood meal and urine. Even so, the only time I use an inoculant or activator is when I add a large supply of fresh material. My organic addition of choice to help stimulate additional microbial decomposition, especially at this earliest stage, is existing compost from a neighboring bin.

Build your compost the way its discussed throughout this post and you will have compost as quickly as possible without the need for supplemental accelerators. If you find your in-process compost is cooling down and stalling out, the addition of nitrogen-rich organic ingredients, along with turning and added moisture, can help jump start a stalled pile.

The bottom line is this: focus on the basics of creating a healthy, balanced composting environment. That is what best determines how quickly feedstock becomes finished compost.

Organic Fertilizer Supplements in Compost

There are two questions I frequently get from new and experienced composters: “What can I add to compost to enhance nutrient levels?” and “Should I supplement composted beds with fertilizer?”

Regarding the first question, the greater the variety of materials used to make compost, the greater the diversity of nutrients within the finished product, including minor elements and micronutrients. If you add a diverse array of ingredients to make your compost, you should have a balanced, nutrient-rich amendment that is sufficient to feed your soil and plants all the elements they need to thrive.

In my case, I never supplement existing compost in the making with additional organic nutrients. However, if you feel the need, there’s no harm if doing so in moderation and using organic inputs.

SOME OF THE MOST COMMON ORGANIC PRIMARY NUTRIENTS THAT COULD BE ADDED TO COMPOST INCLUDE:

1. NITROGEN: Dried blood, blood meal, cottonseed meal, fish emulsion and seaweed extract

2. PHOSPHORUS: Bone meal, rock phosphate

3. POTASSIUM: Greensand, sulfate of potash

Regarding the question about adding organic fertilizer to composted beds, my answer to this question is similar to the first. While you could apply additional fertilizer, you don’t need to but it won’t hurt under the right conditions. That said, I would not add synthetic, salt-based fertilizers. The main premise of using compost is to feed the soil so the soil can feed the plants. Adding synthetic fertilizers will feed the plants, but not the soil. In fact, it can have a detrimental impact on the soil due to the high salt content.

While compost contains a wide array of nutrients, the biggest benefit is in its ability to improve the quality of soil and facilitate what nature does best when given the best conditions. Compost does that. The supplemental nutrients I occasionally add do not detract from what compost is doing. It simply adds an additional and complementary boost of organic nutrients.

Newspapers, Magazines, Copy Paper and Glossy Circulars

I love emptying the contents of my shredder whenever it gets full. It’s such an easy way to bulk up the ingredients of your carbon/brown source of organic matter. The best part, I diverted it from the landfill and this paper becomes unrecognizable within two weeks.

Manure: What You Need to Know Before Adding it to Compost

I would be remiss if I did not warn you against the potential hazards of using horse manure tainted with persistent herbicides. They will not break down in your compost pile. It’s a very sad and unfortunate situation for home gardeners but a very real possibility for anyone using horse manure. It can kill or severely maim certain garden plants, especially tomatoes. It happened to me and I knew better.

If you’d like to learn more about what I call killer compost, it’s addressed thoroughly on separate internet sites where you can learn much more, including how to easily test composted manure before adding it to compost or in your garden beds. I highly recommend you read up on this if you ever think about using horse manure in your compost or garden.

Finally, never add manure from any carnivorous creature. That especially includes dogs, cats and, yes, humans. Very dangerous pathogens can be found in this that are absent from herbivorous animals.